Scientists are constantly learning more about psoriatic arthritis (PsA), a type of arthritis in which a person’s own immune system launches an inflammatory attack on healthy joints and skin.
Understanding as much as you can about PsA can help you cope with the often unpredictable disease. Here, five facts that will deepen your understanding of PsA.
1. There are five distinct types of PsA.
- Symmetric psoriatic arthritis affects about 50 percent of people with PsA and multiple, matching pairs of joints on both sides of the body. This type of PsA is the one most similar to rheumatoid arthritis.
- Asymmetric psoriatic arthritis affects about 35 percent of people with PsA. It typically involves one to three joints, but not matching pairs on both sides of the body.
- Distal interphalangeal predominant PsA causes inflammation and stiffness near fingertips and toes, as well as nail changes including pitting, discoloration and onycholysis (the lifting of the nail away from the nailbed). This type of PsA may be mistaken for osteoarthritis.
- Spondylitis affects the spinal column and can cause pain and stiffness in the neck, lower back, spine, or pelvic joints, making movement more difficult. Spondylitis can also attack connective tissues such as ligaments and cause arthritic changes in other joints.
- Arthritis mutilans is the most severe form of PsA, affecting about 5 percent of people with PsA. It causes deformities in the small joints of the fingers and toes, where people with this type of PsA can lose function. Neck and low back pain are also common.
2. Having scalp or nail psoriasis means an increased risk of developing PsA.
Researchers aren’t sure why, but some think nail damage in particular may be an early sign of PsA because of its link to enthesitis, another characteristic feature of the disease. Enthesitis is inflammation of the sites where ligaments or tendons insert into bone, and people with PsA are prone to developing it in their distal interphalangeal joints, the finger joints closest to the nailbed. The evidence isn’t clear, but some experts think that small, everyday traumas to the fingers could spark an abnormal immune response and persistent inflammation, potentially kick-starting the development of PsA.
3. Injuries and illnesses may trigger the onset of PsA.
As noted above, scientists think that, over time, small bumps, or microtraumas, may lead to changes in the nail and nearby joints and ultimately, PsA. Studies have also found that larger traumas, including musculoskeletal injury; heavy, prolonged lifting; and infections requiring treatment with antibiotics, precede the onset of PsA in up to 9 percent of people.
4. Certain foods can spark PsA flares.
For some, certain foods can trigger flares of joint and skin symptoms. In a survey of more than 1,200 patients with psoriasis and PsA published in 2017 in Dermatologic Therapy, more than 60 percent reported observing that specific foods caused an increase in PsA symptoms. The most common dietary triggers noted were sugar (13.8 percent), alcohol (13.6 percent), gluten (7.2 percent), dairy (6 percent), and vegetables from the nightshade family such as tomatoes (7.4 percent).
5. Losing a little weight can make your biologic more effective.
Many studies have shown people with PsA who carry excess pounds are less likely than their thinner counterparts to achieve what rheumatologists call “minimal disease activity,” or MDA, when treating with biologics. A study published in 2014 in Annals of Rheumatic Disease, however, shows losing just 5 percent of body weight significantly increases the chances of reaching the MDA milestone.
Know your PsA risk
Wondering if you have PsA? Start by asking yourself these five questions. If you're living with PsA and have questions, talk to a NPF Patient Navigator. Whether you were diagnosed yesterday or 20 years ago, your navigator can help you live your healthiest life with PsA.
Driving discovery, creating community
For more than 50 years, we’ve been driving efforts to cure psoriatic disease and improve the lives of those affected. But there’s still plenty to do! Learn how you can help our advocacy team shape the laws and policies that affect people with psoriasis and psoriatic arthritis – in your state and across the country. Help us raise funds to support research by joining Team NPF, where you can walk, run, cycle, play bingo or create your own fundraising event. If you or someone you love needs free, personalized support for living a healthier life with psoriatic disease, contact our Patient Navigation Center. And keep the National Psoriasis Foundation going strong by making a donation today. Together, we will find a cure.
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